Electric circuit breaker



May 30, 1939. D. c. PRINCE 2,160,673

ELECTRIC CIRCUIT BREKER Filed March s, 1938 l alL LEVEL.

1 7 INsuLA-nou INSQLATmN zz a, 16 O 4 O 2l 6\ I7Z6 4, O

la 8 /5 2 2f' Q 1 4' '2,41 Z4 i l l0' 25 2 I s' le 's InvevwtO-r':

@avid C Prince, by Efo/m76 x9--Ja--1v H s Attov'heg.

Patented May 30, 1939 PATENT OFFICE ELECTRIC CIRCUIT BREAKER David C. Prince, Swarthmore, Pa., assignor to General Electric Company, a corporation of New York Application March 3, 1938, Serial No. 193,709

6 Claims.Y (Cl. 2ML-150) My invention relates to electric circuit breakers,

more particularly to those of the multiple-break oil blast type wherein arc pressure generated within an arc-extinguishing liquid, such as oil, is utilized to cause a plurality of liquid blasts through sections of the arc.

A principal object of my invention is the provision of an improved and simplified high voltage oil blast circuit breaker of the multiple-break lo type that is eflicient, rapid and positive in operation, and that is readily adapted to the conventional standard form of oil circuit breakers. My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Fig. l is an elevational view, partly in section, of an oil blast multiple-break circuit breaker embodying the present invention and Fig. 2 is a similar view illustrating another form of my invention.

Fig. 1 illustrates a multiple-break arc interrupting device for one terminal of a conventional tank type oil circuit breaker. Insuch an arrangement a pair of insulating bushings, one of which is indicated at I, extend into the upper part of the tank which contains a suitable arc- 3 extinguishing liquid, such as oil. The arc-extinguishing devices are mounted at the lower ends of the bushings and are immersed in the oil.

Referring more particularly to the structure of a single terminal, the bushing I for the lead-in 3 conductor stud 2 has suitably mounted at the lower end thereof an arc-extinguishing device generally indicated at 3 comprising in the present instance an insulating tube 4 composed of a mechanically-strong insulatingmaterial adapted to withstand high internal pressure. The tube 4 is supported at 6' in a horizontal position by insulating bracing members 5. These members arev also secured at 6 to an adapter structure 1 that isy rigidly `connected to the lead-in bushing 2.

The relatively movable contact structure comprises in the present instance a relatively fixed contact 8 and a movable rod contact 9 separable within the arc chamber 4' and a pair of movablepiston like pressure-operated contacts I9 and II adapted to bridge pairs of xed contacts I2--I3 and I4-I5 respectively, at opposite ends of the chamber. The casing 4 is vented at the ends so that the arc pressure generated at the break 9 9 causes both opening of contacts I0 and II u and a plurality of oil blasts from the arc chamber 4 through the multiple breaks at Il-I2, III-I3 and II-I4, and II-I5.

The movable contact rod 9 is connected to and forms a part of the usual bridging member that is operated -by a lift rod (not shown) along a rectilinear path for opening and closing the circuit. In the closed circuit position shown, the rod contact 9 extends through an opening 9' in the casing 4 and engages in abutting relation the contact 8 that is resiliently mounted for limited lo wipe action in a contact guide and support 9'.

IIn this position the circuit is complete through the breaker along the conducting path, including the adapter 1, conductor I6, terminal I1 of the fixed contact I 5, movable bridging contact 15 II, fixed contact I4 and associated terminal I8, conductor I9, terminal 20 and associated fixed contact I2, movable bridging contact I0, i'lxed contact I3 and associated terminal 2I, flexible conductor 22, fixed contact 8 and the coacting 20 movable contact 9 which connects to the other pole of the breaker.

The movable bridge contacts III and Il are normally biased in opposite directions by springs I9' and II respectively into contact engagement with the corresponding xed contacts. To this end the opposite ends of the tube 4 are provided with insulating abutments 23 which serve both as guides for the contact plungers 24 and seats for the springs III and II'. The tube 4 is like- 30 wise provided with apertures at 25 opposite each of the breaks formed by the bridging contacts so that in the present instance two jets of oil are directed transversely through each of said breaks in accordance with generation of arc pressure 35 within the chamber 4. A pre-requisite of course is that the aforesaid pressure built up to a predetermined value for biasing the bridging contacts against the pressure of springs I9' and II to form said breaks. The exhaust ports 25 can 49 be located with respect to the breaks in any suitable manner for obtaining the cross-blast action and the number of ports can also be varied to suit operating conditions.

The contact plungers 24 are provided with 45 piston-like guide members 24' having apertures as illustrated for permitting reciprocal movement of the contacts within the tube 4. The bridging contacts I0 and II are mounted loosely on extensions 24" of the contact plungers and are 50 centered automatically by concavo-convex washers 26. The washers 26 and also the disc-like contacts I Il and II are apertured as illustrated so that opening movement of the contacts is not retarded.

In operation, lowering of the rod contacty 9 in response to the opening impulse initially causes formation of an arc in the arc chamber 4' defined by the central portion of the tube 4. The pressure generated by this arc builds up within the oil until the bridging contacts I0 and Il are biased against springs I0' and Il to open circuit position. This serves immediately to uncover the exhaust ports 25 opposite each break. At that time oil under pressure is ejected from the arc chamber at high velocity through these ports and across the four arcs formed at the corresponding breaks. In the case of'comparatively high arc currents, the bridging contacts force the members 24' towards the ends of the tube 4 against the bias of springs I0 and Il thereby absorbing part of the excess energy and also uncovering additional ports (where required) so that any desired number of jets of oil are directed across each break. This positive oil blast operation at each of four breaks in series is effective immediately to interrupt the circuit. It will therefore be apparent that positive blast action throughout a wide range of current values is obtained since the arc chamber is not vented at the multiple breaks until a predetermined blast pressure exists.

The bridging contacts I0 and Il after dissipation of arc pressure are again biased to circuitclosing position, the isolating oil gap formed between the contacts 8 and 9 serving to maintain the circuit open.

In the form of my invention shown in Fig. 2, the contact arrangement is generally the same except for the fact that but two breaks are formed by the pressure generated within the tube 4. In this case, the arc pressure formed at the break 8 9 acts on a pair oi pivoted contacts 3l)` and 3| coacting with fixed contacts 32 and 33 respectively to bias said contacts to open` circuit position against the pressure of springs -30 and 3l', and to project oil across the breaks so formed.

The contacts 30 and 3| are pivotally mounted for outward movement with respect to the terminals 20 and I'l respectively and are preferably oi vane-like form for completely or partially closing at opposite ends the arc chamber 4. The springs 30' and 3|' can of course be suitably adjusted so as to permit opening of the contacts only in response to predetermined arc pressure. The exhaust ports for the oil blast are at 34 at opposite ends of the tube 4 and are formed as horizontal slots so that the oil blast tends to sp-lit up the arcs into smaller sections. The arcs can also impinge on arc splitters 34 as shown. As in the previous instance, the isolating oil gap at the break 8-9 serves to maintain open the circuit when the contacts 30 and 3l are returned by their biasing springs to closed circuit position after the arc-interrupting blast.

In both forms of my invention above described it will be noted that the forces produced upon opening of the circuit are substantially balanced due to the symmetrical arrangement, and that no serious lateral thrusts are involved. Also, it will be noted that conventional oil circuit breakers can readily be provided with my improved arc-interrupting device since no material change in the movable contact structure operated by the lift rod is necessarily involved.

It should be understood that my invention is not limited to specic details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An .electric circuit breaker for interrupting high voltage power circuits comprising an insulating arc chamber containing an arc-extinguishing liquid, relatively movable contacts separable in said chamber to form a pressure-generating arc, a plurality of lindependently operable contacts arranged to form a plurality of breaks in series with` said arc, said breaks being located adjacentexhaust ports in said chamber and substantially in symmetrical relation to said pressure-generating arc, and means for biasing said independently movable contacts towards closed circuit position substantially to close said ports in opposition to limited arc pressure in 'said chamber.

2. An electric circuit breaker for interrupting high voltage power `circuits comprising a stationary insulating arc chamber containing an arc-extinguishing liquid, .relatively movable contacts separable in said chamber to form therein a pressure-generating arc, a plurality of independently operable contacts arranged to form a plurality of breaks in series with said arc in accordance with predetermined arc pressure in said chamber, said breaks being located adjacent exhaust ports in said chamber and at opposite sides of said pressure-generating arc so that the mechanical forces acting laterally on said arc chamber are substantially balanced, and means for biasing said independently movable contacts towards closed circuit position in opposition to limited arc pressure in said chamber so as to restrict exhaust of liquid at said ports.

3. An electric circuit breaker comprising a stationary insulating tubular housing forming an arc chamber, the longitudinal axis thereof being horizontally disposed, an arc-extinguishing liquid in said chamber, means forming pressure exhaust openings at opposite ends of said tubular housing, relatively movable contacts separable in said chamber intermediate saidexhaust openings to form a pressure-generating arc, a plurality of independently operable contacts arranged to form a plurality of breaks in accordance with predetermined arc pressure in said chamber, said breaks being located adjacent said exhaust ports and in symmetrical relation to said pressuregenerating arc, and spring means for biasing said independently operable contacts toward closed circuit position whereby said contacts function substantially to close said ports, said spring means permitting opening of said contacts only in accordance with predetermined arc pressure in said chamber.

4. An electric circuit breaker comprising an insulating tubular housing forming an arc chamber, an arc-extinguishing liquid in said chamber, a pair of contacts including a contact movable through a wall of said chamber separable upon initial opening of the circuit to form a pressuregenerating arc in said chamber, said chamber having pressure relief openings at opposite ends of said tubular housing, a pair of independently movable contacts separable to form a plurality of breaks in series with said pressure-generating arc disposed at opposite sides of and symmetrically with relation to said pair of contacts, and spring means normally biasing said independently movable contacts towards closed circuit position for substantially closing said exhaust ports, said springs yielding to predetermined arc pressure in said chamber for permitting opening of said contacts under duid pressure and passage of liquid through the aforesaid exhaust ports for interrupting arcing at said breaks.

5. An electric circuit breaker comprising an insulating tubular housing forming an arc chamber, an arc-extinguishing liquid in said chamber, relatively movable contacts separable at an intermediate point in' said chamber to form a pressure-generating arc, a pair of disk-like contacts operable independently of said rst-named contacts positioned adjacent opposite ends of said chamber and normally closing the same, said disk-like contacts arranged to form a plurality of breaks in series with said pressure-generating arc, and spring means for biasing said disk contacts into closed circuit position in the absence of predetermined arc pressure in said chamber, said chamber having pressure exhaust ports which arc'uncovered in accordance with circuitopening movementl of said disk contacts in response to predetermined arc pressure in said chamber for directing a plurality of jets of arcextinguishing liquid through said breaks.

6. An electric circuit breaker comprising an insulating tubular housing forming an arc chamber, an arc-extinguishing liquid in said chamber, a pair of contacts separable at an intermediate point in said chamber, said chamber having pressure exhaust ports at the opposite ends of said tubular housing in substantially symmetrical relation to said separable contacts, and a pair of pivoted contacts disposed adjacent said exhaust ports and normally biased to close said chamber, separation of said first-named contacts upon initial opening of the circuit causing arc pressure in said chamber that is effective at a predetermined value to bias open said pivoted contacts and to project a plurality of jets of arc-extinguishing liquid through the corresponding breaks by way of said exhaust ports.

DAVID C. PRINCE. 

